i just checked the achievement list and saw that some of them are related to so called what-if-missions.
i know nothing about it, do you ?

One for Resistance, one for Security. Basically an alternate ending where something really bad happens. For example, the Resistance what-if mission has you blowing up a nuclear reactor.

Yup. They're basically a what-if scenario within the different campaigns. Pretty much "what if this happened instead of that. Non-canonical to the storyline you're playing.

sweet, sounds pretty cool, is that more or less confirmed information about resistance what-if-mission? and security? where did you got this info

there are 2 what-if missions per side

No word about Security, and I don't really remember where I got that info. I know this Resistance "what-if" mission was the E3 video, but I don't remember which interview said that it was a what-if mission. Sorry.

@Solarcrest
There is only 1 per side. There are 8 regular maps, plus 1 what if mission for each side, bringing the total to 10.

Actually it is confirmed that there is one "What If" per side but you play it from both perspectives. So you play the Resistance one as Resistance and Security and same with the Security one. That brings the total to 2 missions played form 2 viewpoints, so there i guess there would be 4. Did I read your post wrong, and this is what you meant or did you think that there would be 2 "What Ifs" per side amounting to 8 when played on both sides?

they only have discussed 1 from each side but there are 2 each side

source?

There are 2 what-if maps, thus 4 what-if missions.

This is what I meant; there's only 2 maps, one where the Security does something non-canon, and one where the Resistance does.

Nope.

Every map has 2 missions.

Presumably one Resistance, one Security.

There are 2 maps, and on both, there's a Security and a Resistance what-if mission.

wait whaaat!? 8 regular maps?! does that mean 8 story based maps, like 8 missions for resistance, and 8 for security?! 8 maps and 16 playable missions?

Yes.